If ever 47 minutes illustrated the frustration, tantalizing promise and ambivalence of a second term, this was it.

President Barack Obama, marking the 100th day since he delivered an ambitious inaugural address brimming with expansive plans, sparred with the White House press over a succession of issues over which he has conspicuously clipped control — from his response to the “game-changer” revelation that Syrian government forces used sarin gas, to the failure of his gun control push, to his continued efforts to shutter the Guantanamo Bay detention facility over the objections of Congressional Republicans and Democrats.

“Mr. President, you are a hundred days into your second term…my question to you is do you still have the juice to get the rest of your agenda through this Congress?” asked ABC’s Jonathan Karl — eliciting a surprised chuckle and “goll-y” from the commander-in-chief during a Tuesday morning press conference in the White House briefing room.

“You know… as Mark Twain said, you know, rumors of my demise may be a little exaggerated at this point,” said Obama, who seemed a lot less lighthearted than during his sharp-elbowed stand-up routine at the White House Correspondents Association dinner on Saturday.

Obama isn’t close to being powerless, five months after a convincing second-term victory that left Republicans in a state of agitated soul-searching. His approval rating remains above 50 percent most weeks in most polls, he’s far and away the most trusted figure in Washington, and on the majority of big issues — from background checks to the debt ceiling — he has public opinion firmly on his side.

Yet he finds himself hemmed in by the familiar constraints of partisanship, world events and the shackles of his own commitments.

When it comes to Syria, Obama seems intent on not repeating the mistakes of George W. Bush in Iraq — even as his critics accuse him of replicating the errors of Bill Clinton in Rwanda.

“When I am making decisions about America’s national security and the potential for taking additional action in response to chemical weapon use, I’ve got to make sure I’ve got the facts,” he said . “That’s what the American people would expect. And if we end up rushing to judgment without hard effective evidence, then we can find ourselves in a position where we can’t mobilize the international community.”

Obama has said that the use of chemical weapons would cross a “red line” and be a “game-changer” but he downplayed that rhetoric Tuesday, saying only that the discovery would force him to “rethink the range of options that are available to us.”

Sen. John McCain (R-Ariz.), who has urged intervention, wasn’t impressed, tweeting, “The President says nothing new on #Syria, and the massacre goes on…”

Another commitment that might handcuff for Obama is the implementation of he state and federal health care exchanges mandated by the Affordable Care Act, which go into effect later this year. Democrats have fretted that the new protocol of taxes and complex application procedures will hurt them in the 2014 midterms — and Sen. Max Baucus (D-Mont.), who played a critical role drafting the bill, has warned it could be a “train wreck.”

Just before White House Press Secretary Jay Carney tweeted news of the press conference early Tuesday, administration officials announced the creation of a shortened, easier-to-complete benefits application — an attempt to ease the complex implementation process.

For his part, Obama tried to downplay the threat of Obamacare, even as Democratic Congressional candidates — including South Carolina Congressional hopeful Elizabeth Colbert Busch — distance themselves from the process.

“[F]or the average American out there, for the 85 to 90 percent of Americans who already have health insurance, this thing’s already happened, and their only impact is that their insurance is stronger, better, more secure than it was before. Full stop. That’s it. Now they don’t have to worry about anything else,” Obama said.

But he did concede that the long-time opposition of Govs. Rick Perry in Texas and Rick Scott in Florida, who refused to set up their own local exchanges, made the task tougher than it had to be.

“[W]hen you’re doing it nationwide, relatively fast, and you’ve got half of Congress who is determined to try to block implementation and not adequately funding implementation, and then you’ve got a number of governors — Republican governors — who know that it’s bad politics for them to try to implement this effectively — and some even who have decided to implement it and then their Republican-controlled state legislatures say don’t implement and won’t pass enabling legislation — when you have that kind of situation, that makes it harder.”

It wasn’t all gloom and grind-it-out. One bright spot was the immigration reform bill being drafted by a bipartisan Gang of Eight in the Senate, which could hit the floor by June. Obama said passage would be an “historic achievement” and suggested it could improve the prospects of other collaborations.

On fiscal issues, he said that some Senate Republicans have shown a desire to “move past not only sequester but Washington dysfunction. Whether or not we can get it done, we’ll see.”

Obama defended his decision to support a bill that ends furloughs for FAA employees while other sequester cuts continue to persist. It’s a rare instance in which members of Congress have thought about the needs of their constituents and the American people, he said.

Though critics said Obama was “crying wolf, he’s Chicken Little” in warning of the potential damage done by sequestration, the president insisted that the effects of the cuts have been in line with the administration’s warnings.

While Obama continues to push on his domestic priorities, he said he will also lead an effort to reconsider how the United States brings suspected terrorists to justice more than a decade after the Sept. 11, 2001, attacks. “We should be wiser about how we prosecute terrorists. Period,” he said.

He will “examine every option that we have administratively to try to deal with this issue, but ultimately we’re going to need some help from Congress and I’m going to ask some folks over there who, you know, care about fighting terrorism but also care about who we are as a people to step up and help me on it,” he said. That includes an effort to “reengage” with Congress on closing the U.S. detention facility at Guantanamo Bay.

“This is not something that’s in the best interest of the American people. And it is not sustainable,” he said, though he didn’t say what he’d want to do with the detainees there.

As Obama headed back into the West Wing after spending about 45 minutes behind the briefing room lectern, he was drawn back to the microphone by a shouted question about Jason Collins, the NBA player who came out publicly in a Sports Illustrated column published Monday.

The president said he spoke to Collins on Monday and “told him I couldn’t be prouder.” Collins’s comfort in revealing that he is gay is “one of the extraordinary measures of progress that we’ve seen in this country has been the recognition that the LGBT community deserves full equality, not just partial equality, not just tolerance, but a recognition that they’re fully part of the American family,” the president said.

It’s a major milestone, he added, that someone “who’s excelled at the highest levels in one of the major sports to say, ‘This is who I am, I’m proud of it, I’m still a great competitor. I’m still seven foot tall and can bang with Shaq and deliver a hard foul.’”

Reflecting on the press conference, Obama’s first-term press secretary, Robert Gibbs, acknowledged that this last comment might mean as much — or more — as anything else the president said Tuesday.

“Even as their influence may wane in Congress,” Gibbs said on MSNBC, “they still have the ability with things like this to make a comment and to have it reflect the values of the country.”